Cefalexin contains cefalexin (cephalexin), a first-generation cephalosporin antibiotic used to treat a wide range of bacterial infections. Bacterial infections occur when harmful bacteria multiply in the body and cause inflammation, pain, fever, or tissue damage. Cefalexin works by interfering with bacterial cell wall formation, causing bacterial cells to weaken and die. Cefalexin may be prescribed for respiratory tract infections, skin infections, urinary tract infections, and other susceptible bacterial conditions. It can be used alone or as part of a broader antibiotic treatment plan, depending on the type and severity of infection.

Cefalexin contains cefalexin, a broad-spectrum antibiotic belonging to the first-generation cephalosporin class, commonly used to treat infections caused by susceptible bacteria. It works by preventing bacteria from forming a protective cell wall, an essential structure required for bacterial survival.

Cefalexin is active against many gram-positive bacteria and selected gram-negative organisms, making it useful for several common community-acquired infections. By weakening the bacterial cell wall, the medicine causes bacterial destruction and helps clear infection from the body.

Cefalexin is commonly prescribed for skin and soft tissue infections, throat infections, ear infections, respiratory tract infections, urinary tract infections, and bone infections. It is also used in dental infections and certain post-surgical bacterial infections when indicated.

The medicine usually begins working within a few hours of the first dose, although noticeable symptom improvement may take 1-3 days depending on the severity of infection. Cefalexin is absorbed well after oral administration and is mainly eliminated unchanged through the kidneys, making dose adjustment important in patients with reduced kidney function. When taken as prescribed and for the full recommended duration, Cefalexin is an effective and well-tolerated antibiotic for eliminating bacterial infections and preventing complications.

Respiratory Tract Infections

Treatment of bacterial throat infections, tonsillitis, bronchitis, and certain respiratory infections.

Urinary Tract Infections (UTIs)

Used for uncomplicated urinary infections caused by susceptible bacteria.

Skin and Soft Tissue Infections

Treatment of cellulitis, infected wounds, boils, and skin abscesses.

Ear and Sinus Infections

Used in selected bacterial ear infections and sinusitis.

Bone and Joint Infections

Sometimes prescribed for osteomyelitis or related bacterial infections under specialist guidance.

• Broad Antibacterial Activity: Effective against many common bacteria causing community-acquired infections.

• Rapid Infection Control: Begins reducing bacterial growth soon after administration.

• Good Oral Absorption: Absorbed efficiently when taken by mouth, allowing reliable outpatient treatment.

• Well Tolerated: Generally causes fewer serious side effects when used appropriately.

• Useful Across Multiple Infection Sites: Can treat infections affecting the skin, throat, urinary tract, and soft tissues.

• Suitable for Step-Down Therapy: Often used after injectable antibiotics when symptoms improve.

When taken as directed, Cefalexin is generally well tolerated. Side effects are usually mild and often improve once treatment continues or ends.

Common Side Effects

• Nausea and Stomach Discomfort: Mild digestive upset may occur after doses.

• Diarrhoea: Loose stools can occur due to changes in normal gut bacteria.

• Headache: Mild headache is occasionally reported.

• Skin Rash: Mild allergic skin reactions may occur in some patients.

Uncommon Side Effects

• Vomiting: Some individuals may experience nausea severe enough to cause vomiting.

• Dizziness: Light-headedness may occasionally occur.

• Vaginal Yeast Infection: Antibiotics may disturb normal microbial balance.

Serious Side Effects (Require Immediate Medical Attention)

• Severe Allergic Reactions: Swelling of face, difficulty breathing, widespread rash.

• Severe Diarrhoea: Persistent diarrhoea may suggest antibiotic-associated colitis.

• Blood in Urine: Rare kidney-related reactions may occur.

• Severe Skin Reactions: Blistering or peeling skin requires urgent review.

Cefalexin should be taken exactly as prescribed by your physician. The usual adult dose depends on infection type and severity, often 250 mg to 500 mg every 6 to 12 hours. Tablets or capsules can be taken with or without food, although taking them after food may reduce stomach upset. Swallow with water and complete the full prescribed course even if symptoms improve earlier.

The mechanism of Cefalexin is based on its ability to inhibit bacterial cell wall synthesis, which is essential for bacterial survival and growth. Cefalexin is a first-generation cephalosporin antibiotic that acts by binding to penicillin-binding proteins (PBPs) located inside the bacterial cell wall.

These proteins are responsible for the final stages of peptidoglycan synthesis, a key structural component that gives the bacterial cell wall its strength and rigidity. By binding to PBPs, Cefalexin blocks the cross-linking of peptidoglycan chains, weakening the cell wall structure.

As a result, the bacterial cell wall becomes unstable and unable to withstand internal osmotic pressure, leading to cell lysis and bacterial death. This bactericidal action makes Cefalexin effective against susceptible bacteria causing infections in the respiratory tract, skin, urinary tract, and soft tissues. Because human cells do not contain cell walls, Cefalexin selectively targets bacterial cells without directly damaging human tissues.

• Complete the Course: Finish the full antibiotic course even if symptoms improve early.

• Take at Regular Intervals: Maintain even timing for stable antibacterial levels.

• Monitor Allergic Symptoms: Report rash, swelling, or breathing difficulty immediately.

• Hydration Matters: Adequate fluid intake supports kidney elimination.

• Avoid Self-Medication: Antibiotics should only be used when prescribed.

• Watch for Severe Diarrhoea: Persistent diarrhoea may indicate antibiotic-related bowel infection.

• Kidney Monitoring: Dose adjustment may be needed in reduced kidney function.

While Cefalexin can be taken with or without food, some dietary factors may influence tolerability.

• Alcohol (Moderate): May worsen gastric discomfort.

• Heavy Meals (Low): Food may slightly slow absorption but does not reduce effectiveness.

• Probiotics (Moderate): May help reduce antibiotic-related diarrhoea when spaced apart.

• Acidic Foods (Low): No major effect on absorption.

• Hydration (High): Adequate fluid intake supports safe kidney elimination.

Cefalexin can interact with certain medicines.

• Probenecid (Moderate-High): May increase cefalexin blood levels.

• Metformin (Moderate): May alter metformin elimination.

• Warfarin (Moderate): May increase bleeding tendency in some patients.

• Diuretics (Moderate): Combined kidney monitoring may be needed.

• Other Antibiotics (Moderate): Some combinations may alter antibacterial effect.

• Live Bacterial Vaccines (Low-Moderate): Antibiotics may reduce vaccine effectiveness.

Cefalexin should be used carefully in certain conditions.

• Penicillin Allergy (High): Cross-reactivity may occur in some patients.

• Kidney Disease (High): Reduced elimination increases accumulation risk.

• Severe Gastrointestinal Disease (Moderate): May worsen diarrhoea-related conditions.

• History of Colitis (Moderate): Antibiotics may trigger relapse.

• Diabetes (Low-Moderate): Certain urine sugar tests may be affected.

If you miss a dose, take it as soon as you remember. If it is nearly time for the next scheduled dose, skip the missed one and continue normally. Do not take a double dose. Missing doses may reduce antibacterial effectiveness and increase resistance risk.